I would like the heading styles to work so that the next line will automatically default to the correct heading or default text style.
Any paragraph style may cause a style change when Enter is pressed.
To configure this switch, open the style definition (I assume you know how to do it since you seem to use styles) and go to the Organizer tab.
The Next Style setting designates the style which will be used after Enter. Choose from the drop-down menu.
CAUTION! CAUTION! Your question mentions "default text style*. CAUTION AGAIN! Contrary to what the name might suggest, Default Style is not the style to use for your text. You should use Text Body for that. Default Style is meant to define (and propagate) default settings for all other styles.
Unless you already changed configuration of Heading n, these styles automatically change to Text Body after Enter.
To show the community your question has been answered, click the ✓ next to the correct answer, and “upvote” by clicking on the ^ arrow of any helpful answers. These are the mechanisms for communicating the quality of the Q&A on this site. Thanks!
In case you need clarification, edit your question (not an answer) or comment the relevant answer.